Popular Science Monthly/Volume 43/July 1893/Are There Evidences of Man in the Glacial Gravels?
| ARE THERE EVIDENCES OF MAN IN THE GLACIAL GRAVELS? |
By Major J. W. POWELL.
THE geologist studying in the Rocky Mountains is ever astonished at the rapid degradation of mountain forms. Cliffs, peaks, crags, and rocky scaurs are forever tumbling down. The rocks break asunder above and roll down in great slides on the flanks and about the feet of the mountains. As the slopes are thus diminished, gradually the slides are covered with soil, in part through the decay of the rocks themselves, in part by wind-drifted sands, but perhaps in chief part by the washing of the soils above. In this manner a great mountain is ultimately buried by overplacement. This overplacement gradually washes down, to be distributed on still lower grounds, but it is replaced from above from the newly formed soils. The process goes on until the mountain is degraded into hills and the streams have carried away the greater part of the material of the ancient mountain. Now, in studying these mountains, the geologist is always on his guard to distinguish overplacement from foundation structure. When the mountains are all gone the hills are degraded in the same manner, and the process continues until a grand base-level is established, below which degradation can not take place; then the mountains and hills have all been carried away by rivers to the sea. As mountains and hills are degraded, so valley slopes are brought down. The river, meandering now on this side and now on that, increases the length of its course, as every bend throughout the valley is cut back; but ultimately bend works back against bend, until shorter channels are produced. By cutoff channels the course of the river is diminished; by increasing its meanders the course of the river is lengthened; but in the grand operation the one about compensates for the other. In this manner the river is forever rearranging the flood plain. The banks of the stream, left dry by the vicissitudes of river cutting, tumble down, and a bank goes through a process much like that of the mountain slope; and the geologist is ever on the lookout to distinguish overplacement from the rocks of the foundation structure. There are many conditions where this distinction is plain. but there are many other conditions where it is obscure. Let us see how some of these obscurities arise.
In the United States and in British America there is a vast district of country covered with glacial drift. In a period known to geologists as the Glacial epoch deep snows and gigantic accumulations of ice extended from a region far to the northward down into the United States, nearly to the mouth of the Ohio River. The margin of this great ice field stretched from this central point eastward and northward to the Atlantic Ocean, and westward and northward to the Great Plains, while the Rocky Mountains were covered with great ice fields. This enormous ice sheet was ever working southward, and ever melting along its southern boundary. As it moved southward it plowed the mountains, dug down the hills, and generally filled the valleys with the débris; and it spread over much of the great area a vast sheet of rounded gravels, sands, and clays; and it fed the streams from the border of the ice sheet with fine silt that was distributed along the valleys to the Gulf of Mexico. This glacial flour is now recognized as the loess of the South. Since the disappearance of the great ice sheet the glacial formations that were made by it cover much of the dry land. Now, these glacial formations, being composed of incoherent bowlders, gravels, sands, and clays, are pretty easily distinguished from the underlying, more indurated rocks; but rains, brooks, creeks, and rivers have been at work carving new valleys, and remodeling the bluffs, hills, cliffs, and mountains of all the country, and in the process have distributed over the land formed by the glacial ice extensive bodies of overplacement. This overplacement is incoherent, like the glacial formations. There is no difficulty in distinguishing the overplacement from the primeval foundation, but there is great difficulty in distinguishing it from the glacial formations, and it requires nice powers of observation to always make the distinction with certainty. The criteria for distinguishing overplacement from the original glacial formations have been gradually discovered and formulated in the last few years.
In 1882, by act of Congress, the Geological Survey was authorized and directed to make a geological map of the United States. The survey entered upon this work in different parts of the country. Among many problems before it, one of the more important was that of mapping the glacial formations, and in order to do it two things were necessary: First, it was necessary to distinguish the glacial formations from modern overplacement; second, it was necessary to study the history of the glacial action and the various structures which the ice produced, for there are many—such as moraines, osars, kames, and bodies of till, sand, gravel, and bowlders; and it was sought to discover the history of their formation, and especially the history of the entire Glacial epoch. The members of the Geological Survey engaged upon the general work were only to a limited extent occupied with this problem. In the special fields where they were engaged in studying the primeval foundation rocks they also studied the glacial formations and the modern overplacements. But the field was very large, and many geologists in the country had already made observations and engaged in researches of this character. Most of these geologists were professors in the various colleges of the country, and it was decided by the director to enlist these professorial geologists as far as possible to continue the work and solve these problems for the general survey of the United States upon the foundation of observation already begun by them. For this purpose Prof. Chamberlin, then of Beloit College, with Prof. Salisbury, his associate, and many other professorial assistants, were engaged upon the work. Prof. Shaler, of Harvard University, was also enlisted, with a large corps of assistants. Prof. Emerson, of Amherst College, was likewise enlisted, with his assistants; and Prof. Davis, of Harvard University, with his assistants, also took a part. Mr. Gilbert, of the Geological Survey, with his assistants, was studying the lake basins of the far West, but, as their history was involved in the history of the glacial formations, he incidentally took part in this work. Mr. McGee, permanently employed upon the survey, with his assistants, was engaged in studying the estuarine and coastal-plain formations of the Atlantic slope, and he soon discovered that they were involved with the glacial deposits that had come down from the Appalachian Mountains. Besides the men thus occupied, many other volunteers, as professors and students, took part in the work, now here-, now there; so that altogether more than fifty different men engaged in the solving of these great problems. Nearly all the men who engaged in this work soon discovered that the preliminary problem was to formulate the criteria by which modern overplacement is to be distinguished from original glacial formation. As this proceeded it was further discovered that much of the confusion in the study of the glacial rocks themselves was cleared away, and that it was possible to read the record of the old Glacial epoch in such a manner as to discover its history.
So the work went on year after year, in small part by the regular employees of the survey, in chief part by a professorial corps, aided by many volunteers, often university students. Then many of the State geologists were enlisted, and the work proceeded, until at last a vast body of facts has been collected. The men often conferred with one another and visited doubtful points together. The officers of the Geological Survey, the professorial geologists, and the State geologists thus associated themselves voluntarily, and made many excursions together. For example, Mr. McGee believed that he had made some discoveries in Alabama and Mississippi which were inconsistent with conclusions reached by State geologists. Thereupon he conferred with Messrs. Hilgard, formerly of Mississippi, now of the University of California; Smith, of Alabama; Holmes, of North Carolina; Safford, of Tennessee; Hill, of Texas; and Ward, paleobotanist of the Geological Survey; and they visited the region together, all having distinct views somewhat differing from one another. They examined the problems concerning which differences of opinion had arisen, and they all united in a common conclusion. Subsequently Messrs. Chamberlin and Salisbury visited the same region in company with Mr. McGee, and came to substantial agreement with the first party. Such instances of harmonious co-operation have occurred again and again in all portions of the glaciated area. The whole body of men engaged in the research worked together for a common purpose, and were unwilling to publish material conclusions until the facts could be submitted to many minds. They worked with a harmony and a patience for dissenting opinion worthy of such a body of scientific men. Mr. Chamberlin, first the Professor of Geology at Beloit College, afterward President of the University of Wisconsin, and now in charge of the geological department of the new University of Chicago, had the largest share in all this work; he gave more time to it himself and he employed more assistants than any one else; in fact, he was considered the Nestor of the work. He had long before been the State Geologist of Wisconsin, where glacial formations are highly developed, and had made a special study of the subject, and all the workers in the field deferred largely to his judgment in suggesting methods of research.
Occasionally some observer failed to make the necessary discriminations, and dropped out of the work. Among others whom Prof. Chamberlin enlisted was Prof. G. F. Wright, of Oberlin College, who devoted some summer months to these investigations. Now, some of the observations made by Prof. Wright were of value, but he seemed to fail to distinguish overplacement from glacial formation; and, after trying him for two or three seasons, his labors were dispensed with. Thereupon Prof. Wright commenced the preparation of a popular work upon the history of the Ice period. When this came to the knowledge of Prof. Chamberlin, he demurred. Still, Prof. Wright continued his work, and ultimately published his book. On its appearance it was found that he had ignored the conclusions of his co-workers—had practically denied the accuracy of their observations—and had published a work on the history of the Ice period which they believed to be erroneous and misleading. But they let the subject pass with no unfavorable criticism, believing that ultimately the grand results of the combined labors of so many men, when published, would correct all errors.
There is another phase to this question, connected with the science of archæology. I have already set forth the distinction which geologists recognize between overplacement formations and fundamental formations. Certain archæologic problems which have sprung up in late years in the United States are profoundly affected by the discovery and formulation of these distinctions. Many years ago a local observer at Natchez, Miss., claimed to have discovered a human skeleton in the loess of a bluff on the Mississippi River. The loess is a formation contemporaneous with the glacial formation of the North, as previously explained. The discovery of a human skeleton in this situation was believed to prove that man dwelt in the valley of the Mississippi during the loess-forming epoch. The discovery seemed to be of so much importance that the site was visited by Sir Charles Lyell, who on examination at once affirmed that the skeleton was not found in the loess itself, but in the overplacement or modified loess—that is, in the talus of the bluff; and all geologists and archæologists have accepted the decision.
From time to time other supposed discoveries were made in this country; but one after another was abandoned, until a series of discoveries were made along the line of hills which stretch from the Hudson to the James River. This line of hills marks an interesting geological displacement. The country to the seaward of the line has been differentially displaced from the country mountainward by an uplift on the Appalachian side or a downthrow on the ocean side, or both. The displacement has given rise to many rapids and falls in the streams. Above this line of displacement the waters are not navigable, the declivity of the streams being too great; below, tidewater always flows to the foot of the hills. Now, along this line of hills, back and forth from the upper country to the lower, are many glacial gravels, many hills of ancient river gravels, and many hills of estuarine gravels, all of Glacial age. But there are other gravels of still greater age intimately associated with them, and in making the geological survey of the country it became necessary to distinguish the older gravels of Neocene and Cretaceous age from the younger gravels of the Ice period, and it also became necessary to distinguish the overplacement of modern times. In these same gravels certain archaeologists had discovered what they believed to be palæolithic implements; and as some of the gravels were known to be of Glacial age, they supposed them all to be Glacial, and that they thus had evidence that man inhabited the country during the Glacial epoch. These implements were gathered in very great numbers and collected in various museums in the United States, and many collections were sent abroad to the great museums of the world. Several different collectors engaged in this enterprise for some years, and acquired great reputation for their proof of the antiquity of man on this continent, and for their zeal in discovering the evidence; and to recompense them for this work they were made members of many scientific societies throughout the world, and decorated with ribbons, and some were knighted. Geologists, however, held the question more or less in abeyance, not feeling sure of the geological evidence for the age of the formations in which the supposed stone implements were found. Then other discoveries were made in Minnesota and elsewhere; and finally geologists, with some misgivings and many ifs and perchances, accepted the conclusion that Glacial man in America was a reality.
But now the problem of these formations had to be studied geologically in making the map of the United States, for they had to be represented thereon. They were soon found to be of different ages, but had been confused by reason of the overplacement which is so abundant everywhere. At the same time a new class of archæologic investigations began. The first new work of the character was undertaken in the neighborhood of Washington, on Piny Branch. It had been discovered that the gravels of this locality were of Cretaceous age, and if the flaked stones supposed to be found therein were really deposited in situ, then man in America was not only of Glacial age but of Cretaceous age, for the very same class of implements which the Indians made two centuries ago in the valley of the Potomac were also supposed to be found in the Cretaceous gravels as well as in the gravels of the Glacial epoch. Thereupon Mr. Holmes, of the Bureau of Ethnology in the Smithsonian Institution—not a member of the Geological Survey—undertook the investigation, and he commenced by trenching the hills, and worked patiently for months at the problem. He proved that all the supposed stone implements belonged, not in the foundation rocks of Cretaceous age, but in the overplacement. Man, then, was not of Cretaceous age. While these investigations were in progress the American Association and the International Geologic Congress met in Washington, and many of the scientific men visited the ground. Most of the assistants of the Geological Survey visited it, and other geologists, attracted by the problem, came to Washington for the purpose; so that the whole field was surveyed and the evidence weighed by very many of the geologists of the country and of the world, and they all agreed that the stone implements belonged to the overplacement, and might possibly have been deposited within the last three hundred years.
But there were many like finds in Neocene gravels and gravels of Glacial age stretching down into Virginia and northward through Pennsylvania and New Jersey. One after another these gravel sites were explored by Mr. Holmes and his assistants in the same manner, and in every instance it was revealed that the stone objects were found in the overplacement, that in no case could they be found in the underlying rocks. Objects of the same character have been observed all over the United States. Within the last twenty years the writer of this article has seen them made by Indians in the Rocky Mountain region, and they are scattered far and wide over nearly all the gravel hills of this country. This creates a presumption that, where there are so many of modern origin, all may be modern. It has already been mentioned that certain implements of this kind had been found in gravels, supposed to be of Glacial age, in Minnesota. This is known as the Babbitt find. Finally, Mr. Holmes, together with Prof. Winchell, the State Geologist of Minnesota, visited the locality. They made careful examinations, and were entirely satisfied with the evidence that the stone objects of that site were found in overplacement.
Up to this stage one locality had not been examined with care by the new methods—the locality in Trenton, which had especially become historic by reason of the many collections made therefrom for sundry museums; and this Mr. Holmes finally visited. The implements collected had been found mainly, perhaps not wholly, along old banks of streams, and two localities of this nature had furnished many of the objects of the museums. When visited by Mr. Holmes and other geologists, implements could not be found save in the overplacement. The principal of these sites was a low bluff of gravel in the city of Trenton, and property conditions prevented thorough examination of the site by trenching; thus it seemed that final observation by the new methods was no longer possible. But at this stage the authorities of the city of Trenton commenced to dig a sewer parallel to the bluff and but a few steps back from its face—a deep trench to carry a large body of sewage to a distance where it would no longer be noxious to the inhabitants. Shortly after this work began Mr. Holmes again visited the place, and returned from time to time during its progress, and for upward of a month kept an expert assistant watching the progress of the digging. With all the examination made no stone implement was ever found. This led him to the conclusion that the flaked stones originally found on the bank really belonged to the overplacement and not to the foundation formation of Glacial age.
In the fall of 1889 the writer visited Boise City, in Idaho. While stopping at a hotel some gentlemen called on him to show him a figurine which they said they had found in sinking an artesian well in the neighborhood at a depth, if I remember rightly, of more than three hundred feet. The figurine is a little image of a man or woman done in clay and baked. It is not more than an inch and a half in length, and is slender and delicate, more delicate than an ordinary clay pipestem, and altogether exceedingly fragile. Hold the figurine at the height of your eye and let it fall on the hearth at your feet, and it would be shivered into fragments. It was claimed that this figurine had been brought up from the bottom of an artesian well while the men were working, or about the time that they were working at the well, and that as it came out it was discovered. When this story was told the writer, he simply jested with those who claimed to have found it. He had known the Indians that live in the neighborhood, had seen their children play with just such figurines, and had no doubt that the little image had lately belonged to some Indian child, and said the same. While stopping at the hotel different persons spoke about it, and it was always passed off as a jest; and various comments were made about it by various people, some of them claiming that it had given them much sport, and that a good many "tenderfeet" had looked at it and believed it to be genuine; and they seemed rather pleased that I had detected the hoax. When I returned to Washington I related the jest at a dinner table, and afterward it passed out of my mind. In reading Prof. Wright's second book I had many surprises, but none of them greater than when I discovered that this figurine had fallen into his hands, and that he had actually published it as evidence of the great antiquity of man in the valley of the Snake River.
Consider the circumstances. A fragile toy is buried in the sands and gravels and bowlders of a torrential stream. Three hundred feet of materials are accumulated over it from the floods of thousands of years. Then volcanoes burst forth and pour floods of lava over all; and under more than three hundred feet of sands, gravels, clays, and volcanic rocks the fragile figurine remains for centuries, under such magical conditions that the very color of the burning is preserved. Then well-diggers, with a pump drill, hammer and abrade the rocks, and bore a six-inch hole down to this figurine without destroying it, and with a sand-pump bring it to the surface, to be caught by the well-digger: and Prof. Wright believes the story of the figurine, and places it on record in his book!
There are some other cases that ought to be considered, but none of them differs greatly from those given, and enough has already been said.
Now it must here be confessed that a large number of geologists some years ago were willing to acknowledge the validity of the evidence of Glacial man. Many of them had committed themselves to it, and yet when better evidence was brought they were willing to withdraw opinions previously affirmed. The writer himself has entertained a belief in the existence of Glacial man, and there is still some evidence in California that has not yet been examined by the new methods, and it may be that this evidence is good. The writer has much linguistic material that points to the high antiquity of man on this continent. So we will all withhold final judgment until the evidence is in, being perfectly willing to believe in Glacial man, or Tertiary man, or Cretaceous man, if the evidence demands it, and being just as willing to believe that man was introduced on this continent within the last two thousand years, if the evidence demands it. What care we what the truth is, if it is the truth?
Some years ago Mr. McGee found in a lake formation of the West a stone implement, like those still made by the Indians of that country, in beds of an age not greatly differing from those of the gravels of the Eastern shore; and he published his find. In after years he had learned to distinguish overplacement from foundation formation, and he questioned his own conclusions. This was before the present controversy arose, before Mr. Holmes had so skillfully trenched the hills and shown the true age of the stone implements of the Atlantic slope; but still Mr. McGee, warned by his own observations of the difference between overplacement and under-formation, concluded that he might have been too hasty, and published a long article on the subject, from which the following extract is made:
"It is a fair presumption that any unusual object found within, or apparently within, an unconsolidated deposit is an adventitious inclusion. Every cautious field geologist accustomed to the study of unconsolidated superficial deposits quickly learns to question the verity of apparently original inclusions; he may, it is true, exhaust the entire range of hypothesis at his command without satisfying himself that the inclusion is adventitious; yet he is seldom satisfied that he has exhausted the range of possible hypothesis as to the character of the inclusion, and hesitates long before accepting any unusual association as veritable. His case is not that of the invertebrate paleontologist at work in the Palæozoic rocks, to whom a single fossil may carry conviction; for not only are the possibilities of adventitious inclusion indefinitely less in solid strata, but the mineral character of the fossil is commonly identical with that of its matrix, and so affords inherent evidence of the verity of the association. Nowhere, indeed, in the entire range of the complex and sometimes obscure and elusive phenomena of geology is there more reason for withholding final judgment based upon unusual association than in the unconsolidated superficial deposits of the earth; and it is only where there is collateral evidence that such testimony is acceptable to the cautious student. Now, the sediments of Lake Lahontan are generally, and in Walker River canon almost wholly, unconsolidated, and so the probabilities are against the verity of the association."[1]
When Prof. Wright's second book, Man and the Glacial Period, appeared, the subject was one of popular interest, and it was thought that the book would do harm. Thereupon his fellow-workers criticised the book in various scientific journals, and sometimes spoke very disparagingly of it, as being unworthy of acceptance—all intended to warn the public against a book widely advertised and circulated as the greatest contribution that had ever been made to glacial geology. The fact that in support of his pretensions the author. Prof. Wright, signed his name as a member of the United States Geological Survey, was especially offensive to the others who had been engaged under the auspices of the survey, whether as volunteers, professorial assistants, or permanent employees.
When Prof. Wright found his book thus attacked, he skillfully evaded the real issue—the truth or error of his conclusions—and he or certain of his personal friends raised the cry of persecution by the official geologists of the United States. Most of those who criticised him were professorial geologists, like himself, who had aided the Geological Survey with their work. Prof. Wright was thus attacking his fellow-workers in the field, not deigning to make scientific reply to scientific objections, but making only general statements in relation thereto, and turning the issue on the right of geologists to criticise his work, which he assumed was not official, though he had placed his name on his book with an official title.
All this required no reply from me, until at last Mr. Wright enlisted the championship of The Popular Science Monthly. An article by Mr. Claypole, of Ohio, was published in the April number of the journal, making a bitter attack upon the professorial geologists and upon the regular employees of the United States Geological Survey, and in no covert way attacking the administration of the survey itself. This attack, based as it was on error in every paragraph, would still have called for no response from myself, but would have been passed by, had not the editor of the journal attempted to draw a lesson therefrom in condemnation of the work of the Geological Survey and of that of the professorial geologists and volunteer assistants connected with the universities, colleges, and State surveys of the entire country. It seems now to be incumbent upon me to make a simple explanation of the facts. This I have done briefly, with confidence that the editor of The Popular Science Monthly, finding that he has been misled in the matter, will cheerfully correct the impression that his editorial will naturally make upon those unacquainted with the circumstances.
For more than twenty years the writer of this article has been engaged in conducting and supervising scientific research in various portions of the United States. During the history of this work there have been published under his auspices about two hundred volumes, as annual reports, monographs, bulletins, and other miscellaneous works. In all this body of literature there is very little of controversy. The hundreds of men employed have worked together in practical harmony. They have not always agreed, but agreement has been singularly common, and when disagreements have arisen they have been stated courteously and with little exhibition of temper. It is believed that no other publications of the same magnitude can be found in the world where so little controversy is shown and where disagreement is so uniformly courteous. There have been some controversies, but they have been confined to the journals, and have not found their way into the official publications. And the journalistic controversies have been very few; and in only two instances within my knowledge have they been bitter, the case of this book being one of them. The controversy on this subject has not appeared in the official publications, but only in the journals. It has been wholly unofficial.
Prof. Wright stands almost alone in his advocacy of a scientific doctrine. He has a few sympathizers, and some defenders of portions of his theory, but the great body of his work is repudiated by nearly every geologist in America, and especially by the professorial corps. The controversy which broke out in the journals was at the time unknown to the Director of the Geological Survey. He was away from home and an invalid. He had never by word or circumstance directed or suggested it. and knew nothing of it until after it had occurred. Most of the gentlemen who engaged in it and expressed their indignation at what they believed to be a pseudo-scientific work, were connected with universities and colleges, and were wholly out of the jurisdiction of the Geological Survey. Nor are they men accustomed to brook such dictation. Only one of the controversialists was a permanent member of the Geological Survey.
After the above statement, it only remains for the editor of The Popular Science Monthly to render that judgment which the facts demand.
- ↑ American Anthropologist, vol. ii, 1889, pp. 301-312.